war 

=s±±±SS^= 


DEPARTMENT  OF  BUILDINGS 


THE  BUI 


G CODE 


OF  THE 


City  of  Cleveland,  Ohio 


TITLE  X 


REINFORCED  CONCRETE 
CONSTRUCTION 

V.  G.  MAR  AN  I,  Inspector  of  Buildings 
D.  W.  MORROW,  Ass’t  Insp.  of  Buildings 
J.  P.  CROSS,  Engineer  of  Construction 


REVISED  DECEMBER  13,  1911 


W.  R.  Smellie  Printing  Co. 
Caxton  Building 
Cleveland 


27ja)5 


A L t)  l 1 

The  part  of  the  Building  Code,  known  as  Title  X — 
Reinforced  Concrete  Construction,  which  is  here  in- 
eluded  as  Sections  448A  to  473  inclusive,  was  pre- 
pared as  a separate  instrument  under  the  able  direction 
of  Virgil  G.  Marani,  C.  E. ; Inspector  of  Buildings, 
largely  by  James  P.  Cross,  C.  E. ; Engineer  of  Con- 
struction, with  the  assistance  of  David  W.  Morrow, 
B.  S. ; Assistant  Inspector  of  Buildings. 

This  important  work  is  the  result  of  much  study 
and  research,  combined  with  the  experience  of  en- 
forcing the  present  regulations,  pertaining  to  Rein- 
forced Concrete  Construction. 

A great  many  engineers  were  consulted,  as  well 
as  the  committee  appointed  by  the  Builder’s  Exchange 
and  the  Honorary  Advisory  Committee  of  the  Build- 
ing Department. 


Acknowledgment  of  assistance  is  given  to  the  fol- 
lowing Civil  Engineers : B.  L.  Green,  C.  E. ; S.  W. 
Emerson,  C.  E. ; W.  J.  Watson,  C.  E. ; H.  E.  Mer- 
tens,  C.  E. ; and  W.  O.  Henderer,  C.  E. 


The  entire  work  was  presented  to  the  Honorary 
Advisory  Commission  of  the  Building  Department, 
and  J.  W.  Frazier,  C.  E. ; Secretary,  gave  valuable 
assistance  and  suggestions. 

^This  revised  portion  of  the  Building  Code  was  first 
accomplished  because  of  its  importance;  but,  is  only 
a beginning  of  the  efforts  put  forth  in  the  past  two 
years  by  Virgil  G.  Marani,  C.  E. ; Inspector  of  Build- 
ings, to  thoroughly  revise  and  recodify  the  present  code. 


v... 


Mr.  Virgil  G.  Marani, 
Inspector  of  Buildings, 
Cleveland,  Ohio. 


October  7th,  1911. 


Dear  Sir : 

This  is  to  notify  you  that  at  a meeting  of  the 
Advisory  Commission,  held  October  4th,  at  2 P.  M., 
the  proposed  revision  of  the  reinforced  concrete  sec- 


1 


tion  of  the  Cleveland  Building  Code,  submitted  by 
you,  was  carefully  gone  over  by  them. 

The  followinig  is  an  abstract  from  the  minutes  of 
that  meeting. 

“A  motion  was  made  by  Mr.  Striebinger,  seconded 
by  Mr.  Werk,  instructing  the  Secretary  to  advise  Mr. 
Marani  in  writing  that  the  Commission  has  examined 
the  proposed  revision  of  the  reinforced  concrete  sec- 
tion of  the  Cleveland  Building  Code,  prepared  and 
submitted  by  the  Buildipg  Inspector,  that  same  meets 
with  their  approval  and  they  recommend  that  Mr. 
Marani  submit  it  to  the  Council  at  its  next  regular 
meeting,  with  the  request  that  they  take  action  upon 
same  at  an  early  date.” 

Yours  very  truly, 

(Signed)  J.  W.  Frazier, 

Secretary,. 


2 


ORDINANCE  NO.  22783. 


AN  ORDINANCE  to  ammend  Title  X,  Concrete 
Construction,  Sections  448,  449,  450,  451,  452.  453, 
454,  455,  456,  457,  458,  459,  460,  461,  462/  463, 
464,  465,  467,  468,  469,  470,  471,  472  and  473  in- 
clusive of  the  Revised  Ordinances  of  1907,  Build- 
ing Code,  relating  to  the  erection  of  Concrete  Build- 
ings and  Structures. 

Now,  therefore,  be  it  ordained  by  the  Council  of 
the  City  of  Cleveland,  State  of  Ohio,  that : 

Section  1.  That  Title  X,  Concrete  Construction, 
Sections  448,  449,  450,  451,  452,  453,  454,  455,  456, 
457,  458,  459,  460,  461,  462,  463,  464,  465,  466,  467, 
468,  469,  470,  471,  472  and  473  inclusive  of  the  Re- 
vised Ordinances  of  1907,  Building  Code,  be  amended 
to  read  as  follows: 

TITLE  X. 

REINFORCED  CONCRETE  CONSTRUCTION. 

— Index — 

Section  448  (A). 

448  Reinforced  Concrete — Definition. 

449  Requirements  for  Drawings. 

450  Reinforced  Concrete  Unit  Stresses. 

451  Designs  for  Slabs — Beams  and  Girders. 

452  Limiting  Width  of  Tee  Beams. 

453  Web  Stresses. 

454  Square  and  Rectangular  Slabs. 

455  Flat  Slab  Type  of  Construction. 

456  Reinforced  Concrete  Columns. 

457  Spiral  Reinforced  Columns. 

458  Structural  Steel  Columns  Encased  in  Concrete. 

459  Column  Splices. 

460  Curtain  Walls  in  Skeleton  Construction  Build- 
ings. 

461  Minimum  Thickness  of  Slabs. 

462  Fireproofing. 

463  System. 

464  Proportions  ‘for  Mixing  Reinforced  Concrete. 

465  Cement  Sand  and  Inerts. 

466  Steel  in  Concrete. 


3 


467  Placing  Concrete  and  Steel. 

468  Freezing  Weather. 

469  Centering  and  Forms. 

470  Inspecting  and  Tests. 

471  Concrete  Block  Construction. 

472  Tests  of  Concrete  Blocks. 

473  Requirements  and  Conditions  of  Approval — 
Revocal  of  License. 

TITLE  X. 

REINFORCED  CONCRETE  CONSTRUCTION. 

REINFORCED  CONCRETE— DEFINITION. 

Section  448  (B).  By  reinforced  concrete  is  meant 
concrete  in  which  steel  is  imbedded  in  such  a position 
that  it  shall  resist  all  tensile  stresses  and  assist  in  the 
resistance  of  shear  along  proper  structural  lines  so  that 
the  stresses  in  the  combination  can  be  ascertained  by 
computation  and  verified  by  tests. 

The  concrete  shall  be  mixed  in  such  proportion  and 
so  handled  that  after  it  is  placed  in  the  forms,  all 
voids  in  the  aggregate  will  be  filled  with  mortar  and 
all  voids  in  the  mortar  filled  with  cement.  Thirty  (30) 
days  after  mixing,  it  shall  develop  a crushing  strength 
of  two  thousand  (2,000)  pounds  per  square  inch,  by 
testing  a six  (6)  inch  cube. 

REQUIREMENTS  FOR  DRAWINGS. 

Section  449.  Before  a permit  shall  be  issued  for  a 
reinforced  concrete  building  or  structure,  complete 
working  drawings,  details  and  specifications  shall  be 
filed  with  the  Department  of  Buildings,  giving  the 
size  and  location  of  members,  the  size  and  position 
of  reinforcing  rods,  stirrups,  bent  rods  and  any  other 
information  necessary  for  the  proper  calculation  of 
the  structure  or  building.  The  Department  of  Build- 
ings reserves  the  right  to  demand  that  the  owner, 
architect  or  engineer  submit  a certified  copy  of  such 
computation  or  stress  sheets  for  examination  upon  ap- 
plication for  a building  permit. 

The  Department  of  Buildings,  in  granting  a permit 
to  erect  any  reinforced  concrete  structure,  does  not, 


4 


in  any  manner,  pass  the  construction  until  after  tests 
have  been  made  of  the  actual  construction  to  their 
satisfaction. 

REINFORCED  CONCRETE  UNIT  STRESSES. 

Section. 450.  The  following  unit  working  stresses 
shall  not  be  exceeded : 

Iron  in  Tension 

Medium  Steel  in  Tension... 

High  Carbon  Steel  in  Ten- 
sion   

Cold  Twisted  Medium  Steel 

in  Tension ] 

Steel  to  resist  diagonal  Ten- 
sion   1 

Concrete  in  Direct  Com- 
pression   

Concrete  in  direct  Com- 
pression (Spiral  Reinforced 

Columns)  

Concrete-Extreme  Fibre  in 

Compression  

(As  determined  by  the 
straight  line  formula) 

Rond  stresses  for  Plain  High 

Carbon  bars 

Bond  Stresses  for  Plain  Low 

Carbon  Bars  

Bond  stresses  or  Twisted  or 

Deformed  Bars  . . . . T 

Concrete  in  Diagonal  Tension 
NOTE — The  compressive  : 
not  exceed  the  product  of  the  compressive  stress  in 
the  concrete  multiplied  by  the  elastic  modulus  of  the 
steel  and  divided  by  the  elastic  modulus  of  the  con- 
crete. 


12,000 

lbs. 

per 

sq. 

inch. 

16,000 

lbs. 

per 

sq. 

inch. 

18,000 

[ 

lbs. 

per 

sq. 

inch. 

18,000 

lbs. 

per 

sq. 

inch. 

10,000 

lbs. 

per 

sq. 

inch. 

500 

lbs. 

per 

sq. 

inch. 

l 

650 

lbs. 

per 

sq. 

inch. 

L 

700 

k 

lbs. 

per 

sq. 

inch. 

i 

50 

lbs. 

per 

sq. 

inch. 

70 

lbs. 

per 

sq. 

inch. 

100 

lbs. 

per 

sq. 

inch. 

40 

lbs. 

per 

sq. 

inch. 

stress 

in  the  steel 

shall 

DESIGNS  FOR  SLABS,  BEAMS  AND  GIRDERS. 

Section  451.  All  reinforced  concrete  work  shall  be 
designed  in  accordance  with  standard  engineering 
practice  and  the  following  assumptions : 

That  the  ratio  of  moduli  of  elasticity  of  concrete  to 


5 


steel  is  one  (1)  to  fifteen  (IS)  ; That  the  adhesion  of 
the  concrete  to  the  steel  makes  the  two  materials  act 
together;  That  tensile  stresses  are  taken  by  the  steel 
and  that  the  stress  strain  curve  of  concrete  in  com- 
pression is  a straight  line. 

Beams,  slabs  and  girders  shall  be  calculated  as  con- 
tinuous unless  constructed  so  as  to  act  as  simple 
beams.  When  continuous  for  uniform  loads,  the  bend- 
ing moment  at  the  center  shall  be  figured  as  not  less 
WL  WL 

than  for  the  intermediate  spans  and  — 

10  9 

for  the  end  spans,  provided  at  least  sixty-six  (66) 
per  cent,  as  much  reinforcement  is  provided  at  the 
top  over  supports  as  at  the  center  of  the  member ; and 
the  reinforcement  extends  beyond  the  support  a suffi- 
cient distance  to  insure  proper  bond. 

In  all  cases,  however,  beams  and  girders  which  are 
built  monolithic  at  the  supports  shall  have  at  least 
twenty  (20)  per  cent,  as  much  steel  in  the  top  over 
supports  as  at  the  center.  For  concentrated  loads  on 
continuous  beams  or  girders,  the  bending  moment  at 
the  center  shall  be  calculated  as  for  a simple  beam 
and  this  moment  may  be  reduced  twenty  (20)  per 
cent,  for  intermediate  spans  or  ten  (10)  per  cent,  for 
end  spans. 

Where  a short  span  adjoins  a long  span  and  one- 
half  (y2)  of  the  short  span  considered  as  a cantilever 
cannot  produce  a bending  moment  which  will  develop 
the  strength  of  the  reinforcement  over  the  supports, 
the  long  span  shall  be  considered  as  an  end  span. 

For  simple  girders,  beams  or  slabs  the  span  shall 
be  taken  as  the  clear  span  and  for  continuous  girders, 
beams  or  slabs,  the  span  shall  be  taken  as  the  distance 
between  centers  of  supports. 

LIMITING  WIDTH  OF  FLANGE  IN  TEE 
BEAMS. 

Section  452.  When  beams  are  made  monolithic 
with  the  floor  slab  a portion  of  the  floor  may  be  as- 
sumed as  acting  in  flexure  in  combination  with  the 


6 


beam. 

The  width  of  the  slab  so  acting  in  flexure  is  to  be 
governed  by  the  shearing  resistance  between  slab  and 

1 

beam,  but  limited  to  a width  equal  to  one-third  ( — ) 

- 3 

of  the  span  length  of  the  beams  between  supports  and 
also  limited  to  a span  length  of  three-quarters  (J4) 
of  the  distance  from  center  to  center  between  beams. 

No  part  of  the  slab  shall  be  considered  as  a portion 
of  the  rib,  unless  the  slab  and  rib  are  cast  at  the  same 
time. 

Where  reinforced  concrete  girders  support  rein- 
forced concrete  beams,  the  portion  of  the  floor  slab 
acting  as  flange  to  the  girder,  must  be  reinforced  with 
rods  near  the  top,  at  right  angles  to  the  girder  to 
enable  it  to  transmit  local  loads  directly  to  the  girder 
and  not  through  the  beams. 

WEB  STRESSES. 

Section  453.  Where  the  diagonal  tension  exceeds 
forty  (40)  lbs.  per  square  inch,  additional  web  rein- 
forcement of  approved  design  shall  be  used. 

Stirrups  shall  not  be  placed  further  apart  than  two- 

2 

thirds  ( — )D.  if  they  are  considered  as  adding  to  the 
3 

shearing  resistance.  In  no  case  shall  the  shear  ex- 
ceed one  hundred  and  twenty-five  (125)  pounds  per 
square  inch. 

When  reinforcement  is  used  to  increase  the  unit 
shear,  the  proportion  of  the  unit  shear  taken  by  the 
concrete  shall  not  exceed  forty  (40)  lbs.  per  square 
inch,  and  the  reinforcement  shall  be  sufficient  to  take 
the  remainder.  If  unattached  stirrups  are  used  they 
shall  pass  under  the  main  reinforcing  bars. 

There  shall  be  sufficient  anchorage  to  develop  the 
stirrups  above  the  neutral  axis  of  the  beams  without 
exceeding  the  bond  stresses  specified.  If  the  stirrups 
are  attached  to  the  reinforcing  bars  the  connection 
must  be  sufficient  to  develop  the  elastic  limit  of  the 


7 


steel  without  causing  slipping  along  the  main  bars. 

If  the  reinforcing  rods  are  bent  to  approximately 
forty-five  (45)  degrees  and  are  spaced  no  further  apart 
than  “d”  or  if  the  bars  are  bent  at  the  one  quarter 
(T4)  points,  they  may  be  figured  as  shear  members 
in  providing  for  the  excess  shear  over  forty  (40) 
pounds  per  square  inch.  The  notation  “d”  shall  be 
effective  depth. 

SQUARE  AND  RECTANGULAR  SLABS. 
Section  454.  For  square  slabs  with  two  way  rein- 
forcements, the  bending  moment  at  the  center  of  the 

W L2 

slab  shall  be  not  less  than for  intermediate 

20 

W L2 

spans,  and  — for  the  end  spans. 

18 

The  moment  over  supports  shall  be  not  less  than 
W L2 

and  the  sum  of  the  moments  over  one  sup- 

30 

port  and  at  the  center  of  the  span  shall  be  taken  not 
W L2 

less  than , in  which  above  formula  “W”  is  the 

10 

load  per  linear  foot  and  “L”  the  length  of  span. 

For  square  or  rectangular  slabs  the  distribution  of 
the  loads  in  the  two  directions,  shall  be  inversely  as 
the  cubes  of  the  two  dimensions. 

FLAT  SLAB  TYPE  OF  CONSTRUCTION. 
Section  455.  The  type  of  construction  referred 
to  in  this  section  is  a design  of  reinforced  concrete  slab 
supported  by  reinforced  or  structural  steel  columns  * 
with  flaring  heads  and  in  which  beams  and  girders  are 
eliminated. 

This  construction  shall  be  figured  with  a bending 
moment  in  any  quadrant  over  the  column  head  of  not 
W L3 

less  than in  foot  pounds,  in  which  W equals 

27 


8 


total  weight  per  square  foot,  dead  and  live  load.  L 
equals  length  in  feet  of  a side  of  an  equivalent  square 
in  rectangular  panels  and  the  side  of  a square  in 
square  panels.  This  length  shall  be  taken  center 
to  center  of  columns.  In  calculating  the  required  area 
of  steel  in  each  band  at  the  center  of  the  span*,  the 
length  of  span  of  band  shall  be  taken  center  to  center 
of  columns  in  the  above  formula.  The  bands  of  rein- 
forcement shall  be  made  approximately  seven-six- 
7 

teenths  ( — ) L in  width,  in  solving  for  the  required 

16 

area  of  steel  over  the  column  head,  the  distance  from 
the  compressive  face  to  the  plane  of  steel  assumed 
shall  be  from  the  center  of  gravity  of  all  the  steel  to 
the  under  side  of  slab.  Any  additional  steel  required 
over  the  column  head  shall  extend  beyond  the  center 
of  column  a distance  not  less  than  three-tenths  (.3) 
L in  all  directions. 

The  radial  bars  may  be  assumed  as  resisting  tension 
provided  they  are  carried  a distance  horizontally  not 
less  than  one-tenth  (.1)  L each  way  before  bending 
downward;  further,  that  the  allowed  area  of  each 
radial  bar  figured  to  resist  tension  shall  constitute  not 
over  one-half  (J4)  the  area  of  any  single  band  of 
continuous  reinforcement. 

The  diameter  of  interior  spirally  reinforced  con- 
crete columns  shall  never  be  less  than  one-thirteenth 

1 1 

( — ) L for  floors,  or  one-fourteenth  ( — ) L for  roofs 
13  14 

and  the  diameter  of  column  head  shall  never  be  less 
than  two-tenths  (.2)  L and  this  head  if  constructed  of 
concrete  shall  be  dropped  below  the  under  side  of  slab 
at  least  three  (3)  inches  at  the  outer  edge. 

Square  panels  shall  never  be  less  in  thickness  than 

1 

one  forty-fifth  ( — :)  of  the  diagonal  distance  from 
45 

center  to  center  of  columns,  for  floors,  and  not  less 


9 


1 

than  one-fiftieth  ( — ) for  roofs. 

SO 

Rectangular  panels  shall  never  be  less  in  thickness 

1 

than  one  forty-fifth  ( — ) of  the  diagonal  span  of  an 

45 

equivalent  square  center  to  center  of  columns  for 

1 

floors,  and  one-fiftieth  ( — ) for  roofs. 

SO 

The  minimum  thickness  of  slabs  shall  be  six  and 

1 

one-half  (6 — ) inches  for  floors  and  six  (6)  inches 

2 

for  roofs. 

The  required  percentage  of  steel  in  a single  layer 
of  bars  shall  not  exceed  forty-four  one-hundredths 
(.44)  of  one  per  cent,  for  medium  steel,  or  thirty-six 
one-hundredths  (.36)  of  one  per  cent,  for  high  carbon 
steel.  In  any  flat  slab  type  of  construction  provision 
shall  be  made  to  take  care  of  circumferential  stresses. 
In  all  buildings  hereafter  to  be  erected  all  interior 
columns  shall  have  spiral  and  vertical  reinforcement 
or  shall  have  columns  built  of  structural  steel  encased 
in  concrete  and  the  slab  steel  shall  be  so  placed  that  it 
comes  near  the  top  of  slab  at  the  columns  and  shall  be 
held  firmly  in  position  in  such  a manner  that  the  bars 
cannot  be  displaced.  A spacing  and  clamping  device 
satisfactory  to  the  Department  of  Buildings  shall  be 
used  for  the  floor  slab  steel. 

In  end  or  wall  panels  in  which  wall  columns  of  rein- 
forced concrete  with  heads  are  omitted,  allowance 
shall  be  made  for  the  increased  moments.  These  mo- 
ments shall  be  assumed  to  be  ten  (10)  per  cent, 
greater  than  the  moments  in  the  interior  panels. 

If  wall  columns  are  used  they*  shall  be  calculated  to 

1 

carry  one-half  ( — ) the  panel  load  plus  any  other 

2 

loads  and  if  necessary  the  column  shall  be  designed 


10 


for  eccentric  loadings.  The  wall  beams  .shall  be  de- 

1 

signed  to  carry  one-third  ( — ) of  the  panel  load  plus 

3 

any  other  loads.  The  minimum  width  of  wall  beams 
of  reinforced  concrete  shall  be  twelve  inches  and  never 

1 

less  than  one-half  ( — ) the  depth  of  beam. 

2 

REINFORCED  CONCRETE  COLUMNS. 

Section  456.  Reinforced  concrete  columns  shall 
not  exceed  in  length  fifteen  (15)  times  the  least  side 
or  diameter  and  where  such  columns  exceed  twelve 
(12)  times  the  least  diameter  or  side,  the  allowable 
compression  of  the  concrete  shall  be  taken  as  five 
hundred  (500)  pounds  multiplied  by  the  least  side  or 
diameter  of  the  column  in  inches  and  divided  by  the 
unsupported  length  in  feet. 

For  columns  subject  to  eccentric  loading  or  bend- 
ing of  an  indeterminate  amount,  the  above  stress  shall 
be  reduced  at  least  twenty  (20)  per  cent.  When  the 
bending  stresses  in  a column  can  be  definitely  deter- 
mined, the  combined  bending  and  direct  stress  shall 
not  exceed  five  hundred  (500)  pounds  per  square 
inch. 

Columns  with  longitudinal  rods  shall  have  at  least 
one  (1)  square  inch  of  steel  in  the  total  area,  and  not 
less  than  four  (4)  rods;  and  rods  shall  not  be  used 
of  a less  diameter  than  one-half  (*4)  inch.  The 
area  of  the  longitudinal  rods  shall  not  be  less  than 
one-half  (T/2)  of  one  per  cent,  of  the  required  cross 
section  area  of  the  column  and  shall  not  exceed  four 
(4)  per  cent,  of  the  effective  cross  sectional  area  of 
the  column.  The  longitudinal  rods  must  be  tied  to- 
gether to  resist  outward  flexure  at  intervals  not  greater 
than  the  least  width  or  diameter  of  column. 

The  steel  hoops  shall  not  be  less  than  one-quarter 
(J4)  inch  diameter  and  spaced  not  more  than  twelve 
(12)  inches  apart. 


11 


SPIRAL  REINFORCED  COLUMNS. 
SECTION  457. 

Section  456  Modified.  Where  the  reinforcement 
consists  of  vertical  bars  and  spiral  hooping,  the  con- 
crete shall  not  be  stressed  beyond  six  hundred  and 
fifty  (650)  pounds  per  square  inch,  provided  that  the 
amount  of  vertical  reinforcement  be  not  less  than  the 
spiral  reinforcement  nor  greater  than  five  (5)  per 
cent,  of  the  area  within  the  hooping;  that  the  percent- 
age of  spiral  hooping  be  not  less  than  one-half  (}4) 
of  one  per  cent,  and  not  to  exceed  one  and  one-half 
(1/4)  per  cent;  that  the  pitch  of  the  spiral  be  uni- 
form and  not  greater  than  one-eighth  (}4)  of  the 
diameter  of  the  column  nor  greater  than  three  (3) 
inches;  that  the  spiral  be  secured  to  the  verticals  at 
every  intersection  to  insure  the  maintaining  of  its 
form  and  position;  that  the  verticals  be  spaced  so  that 
their  distance  apart,  measured  on  the  circumference,, 
be  not  greater  than  nine  (9)  inches  or  one-eighth  (*/£) 
the  circumference  of  the  column  within  the  hooping. 
In  such  columns,  the  action  of  the  hooping  may  be  con- 

4 

sidered  equal  to  two  and  four-tenths  (2 — ) times  its 

10 

amount  taken  as  vertical  reinforcing.  No  part  of  the 
concrete  outside  of  the  hooping  shall  be  considered 
as  a part  of  the  effective  column  section. 

STRUCTURAL  STEEL  COLUMNS  ENCASED 
IN  CONCRETE. 

Section  458.  Where  structural  steel  columns,  in 
steel  frame  structures  or  structures  in  which  the  loads 
are  transmitted  directly  to  steel  column,  are  encased  in 
concrete,  the  structural  steel  shall  be  proportioned  to 

15 

carry  the  total  dead  load  and  fifteen-sixteenths  ( — ) of 

16 

the  total  live  load  that  can  be  transmitted  to  same  and 
the  concrete  shall  be  proportioned  to  carrv  one-six- 

1 

teenth  ( — ) of  the  live  load  only;  and  in  no  case  shall 
16 


12 


the  unit  stress  in  the  structural  steel  exceed  sixteen 
thousand  (16,000)  pounds  per  square  inch  of  net  steel 
section,  or  shall  the  unit  stress  in  the  concrete  exceed 
five  hundred  (500)  pounds  per  square  inch  of  net  con- 
crete section. 

In  columns  of  this  design  the  concrete  shall  be  rein- 
forced with  spiral  hooping  of  not  less  than  one-half 
(J4)  of  one  (1)  per  cent. 

The  pitch  of  the  spiral  shall  be  uniform  and  not 

1 

greater  than  one-tenth  ( — ) of  the  diameter  of  the 

10 

hooping  nor  greater  than  three  (3)  inches.  The 
spirals  shall  be  secured  at  each  intersection  in  such  a 
manner  as  to  insure  the  maintaining  of  its  form  and 
position. 

No  part  of  the  concrete  outside  of  the  hooping  shall 
be  considered  as  a part  of  the  effective  column  sec- 
tion. 

In  latticed  or  open  web  structural  columns  it  shall 
not  be  necessary  to  use  the  hooping  specified  above. 

In  buildings  with  columns  of  this  design  the  height 
shall  be  limited  to  sixteen  stories  or  two  hundred 
(200)  feet  in  height,  provided  that  the  other  require- 
ments of  this  Code  for  buildings  of  this  height  are  com- 
plied with. 

All  structural  steel  which  is  to  be  encased  in  con- 
crete shall  be  wrapped  with  wire  in  such  a manner  as 
to  insure  the  bonding  of  the  concrete  to  the  steel  and 
no  structural  steel  which  is  to  be  encased  in  concrete 
shall  be  painted  or  oiled.  Before  encasing  structural 
steel  in  concrete,  scale  or  rust  of  any  appreciable 
amount  shall  be  removed. 

COLUMN  SPLICES. 

Section  459.  In  all  buildings  hereafter  to  be  erected 
the  column  splices  shall  be  made  in  such  a manner  as 
to  transmit  the  stresses  for  which  they  are  designed. 
The  connections  shall  be  made  by  turnbuckle,  sleeve 
nut,  slip  sleeve  or  by  lapping  the  rods  and  bolting 
together  in  such  a manner  that  the  stresses  will  be 


13 


transmitted  properly.  If  the  device  used  requires  the 
rod  to  be  threaded  the  effective  area  shall  be  taken  at 
the  root  of  the  thread.  If  a slip  sleeve  is  used  the 
rods  must  have  their  ends  milled  or  equal.  The  dia- 
meter of  the  sleeve  to  be  not  over  one  sixteenth 

1 

(— ) inch  larger  than  the  diameter  of  the  rod.  Where 

16 

the  bearing  is  made  metal  to  metal  the  contact  shall 
be  made  so  as  to  transmit  all  stresses  properly.  Where 
the  rods  are  in  tension  due  to  wind  stresses,  the  con- 
nection shall  be  made  by  means  of  a positive  connec- 
tion. The  use  of  pipe  sleeve  connections  is  prohibited 
unless  they  fit  the  rods  as  above  described.  All  column 
steel  shall  set  directly  in  line  with  the  steel  below  and 
must  be  constructed  in  such  a manner  as  to  eliminate 
any  short  bends  in  the  steel.  The  steel  reinforcement 
shall  be  spliced  at  such  a point  above  the  floor  that  the 
bond  stress  in  the  rod  is  developed  enough  to  carry 
the  increased  load  transmitted  to  it. 

CURTAIN  WALLS  IN  SKELETON  CONSTRUC- 
TION BUILDINGS. 

Section  460.  Buildings  having  a complete  skeleton 
construction  of  steel  or  of  reinforced  concrete  con- 
struction, or  a combination  of  both,  may  have  exterior 
walls  of  reinforced  concrete  eight  inches  thick,  pro- 
vided, however,  that  such  walls  shall  support  only 
their  own  weight  and  that  such  walls  shall  have  steel 
reinforcement  of  not  less  than  three-tenths  (.3)  of 
one  per  cent,  in  each  direction  vertically  and  horizon- 
tally, the  rods  spaced  not  more  than  twelve  (12)  inch 
centers  and  wired  to  each  other  at  each  intersection. 
All  bars  shall  be  lapped  for  a length  sufficient  to 
develop  their  full  stress  for  the  allowable  unit  stress 
for  adhesion.  Additional  bars  shall  be  set  around 
openings,  the  verticals  wired  to  the  nearest  horizontal 
bars,  and  the  horizontal  bars  at  top  and  bottom  of 
openings  shall  be  wired  to  the  nearest  vertical  bars. 

The  steel  rods  shall  be  combined  with  the  concrete 
and  placed  where  the  combination  will  develop  the 


14 


greatest  strength,  and  the  rods  shall  be  staggered  or 
placed  and  secured  so  as  to  resist  a pressure  of  thirty 
(30)  pounds  per  square  foot,  either  from  the  exterior 
or  from  the  interior  on  each  and  every  square  foot 
of  each  wall  panel. 

MINIMUM  THICKNESS  OF  SLABS. 

Section  461.  Reinforced  concrete  slabs  shall  not 
be  less  than  four  (4)  inches  thick  for  floors  and  three 
{3)  inches  for  roofs. 

FIREPROOFING. 

Section  462.  For  the  purpose  of  fire  protection  the 
outer  surface  of  reinforcing  steel  shall  be  kept  away 
from  the  surface  of  the  concrete. 

Two  (2)  inches  in  columns  and  girders. 

One  and  one-half  (1J4)  inches  in  beams. 

Three-quarters  ($4)  inch  in  slabs. 

No  reinforcing  steel  not  protected  from  fire  shall 
be  considered  as  adding  to  the  strength  of  the  con- 
struction. 

Lime  or  hard  wall  plaster  shall  not  be  considered 
as  a fireproofing  material  in  reinforced  concrete  work. 

SYSTEM. 

Section  463.  No  system  of  reinforced  concrete 
shall  be  used  which  is  not  capable  of  design  and  in- 
vestigation in  accordance  with  the  formula  and  prin- 
ciples laid  down  in  this  Code. 

PROPORTION  FOR  MIXING  REINFORCED 
CONCRETE. 

Section  464.  All  reinforced  concrete  shall  be  mixed 
in  the  proportion  of  (1)  one  part  Portland  Cement  to 
(2)  two  parts  clean,  sharp  sand  and  not  more  than  (4) 
four  parts  aggregate.  Where  slag  or  other  similar  ma- 
terial is  used,  the  proportion  of  aggregate  shall  be  re- 
duced in  order  to  have  the  voids  properly  filled.  In 
no  case  shall  more  than  two  (2)  parts  sand  be  used 
to  one  (1)  part  cement  and  all  mixng  shall  be  done 
by  machine,  except  where  limited  quantities  are  re- 
quired or  where  the  conditions  of  the  work  make  hand 


15 


mixing  preferable ; hand  mixing  to  be  done  only  when 
approved  by  the  Department  of  Buildings.  In  all  mix- 
ing the  separate  ingredients  shall  be  measured  and 
shall  be  thoroughly  mixed  and  must  be  uniform  in 
color,  appearance  and  consistency  before  placing. 

CEMENT,  SAND  AND  INERTS. 

Section  465. 

(a)  CEMENT.  Only  Portland  Cement  shall  be 
used  which  conforms  to  the  Standard  Specifications  of 
the  American  Society  for  Testing  Materials. 

All  cement  shall  be  tested  in  lots  of  not  more  than 
one  (1)  car  load,  and  the  Department  of  Buildings 
may  at  any  time  demand  that  certified  copies  of  all 
test  records  be  submitted  for  examination. 

The  minimum  requirements  for  tensile  strength  for 
briquettes  one  (1)  inch  square  in  section  shall  be: 


NEAT  CEMENT. 

24  Hours  in  moist  air 175  lbs. 

7 Days  (one  day  in  air,  six  in  water) 500  lbs. 

28  Days  (one  day  in  air,  twenty-seven  in 

water)  600  lbs. 

ONE  PART  CEMENT,  THREE  PARTS 
STANDARD  SAND. 

7 Days  (one  day  in  air) 200  lbs. 

28  Days  (one  day  in  air,  twenty-seven  in 

water)  275  lbs. 

SAND. 


(b)  The  sand  used  shall  be  clean,  coarse,  sharp, 
natural  sand,  preferably  a mixture,  of  coarse  and  fine 
grains  with  the  coarse  grains  predominating.  The 
maximum  percentage  of  clay  or  loam  shall  not  exceed 
five  (5)  per  cent,  and  at  least  sixty  (60)  per  cent  shall 
be  retained  on  a fifty  (50)  mesh  sieve  and  the  sand 
shall  contain  at  least  ninety  (90)  per  cent  silica. 

AGGREGATE. 

(c)  The  aggregate  shall  consist  of  hard  broken 
stone,  free  from  dust,  clean  gravel,  slag  or  similar 
material  crushed  and  screened  to  pass  a one  (1)  inch 
ring  and  rejected  on  a one-quarter  (J^)  inch  ring. 
Both  sand  and  aggregate  shall  be  subject  to  the  ap- 


16 


proval  of  the  Department  of  Buildings,  which  may 
demand  that  any  material  in  question  be  tested  at  the 
expense  of  the  owner  or  owners,  in  an  approved  test- 
ing laboratory  and  the  certified  results  submitted  to 
the  Department  of  Buildings  to  aid  in  forming  an 
m opinion  as  to  the  fitness  or  unfitness  of  the  material 
for  the  purpose  intended. 

STEEL  IN  CONCRETE. 

* * Section  466.  All  steel  shall  be  tested  by  an  ap- 

proved testing  laboratory  and  the  Department  of 
Buildings  may,  at  any  time,  demand  that  certified 
copies  of  all  test  records  be  submitted  to  it  for  exam- 
ination. All  steel  used  for  reinforcing  purposes  shall 
comply  with  the  “Standard  Specifications”  Governing 
the  Chemical  and  Physical  Properties  of  Concrete  Re- 
inforcing Bars  as  adopted  by  the  Association  of 
American  Steel  Manufacturers,  1910. 

“The  above  modified — 

All  reinforcing  steel  not  rolled  from  billets  shall  be 
rolled  from  standard  section  Tee  rails,  and  shall 
comply  with  the  physical  tests  specified  in  Paragraph 
2 of  the  above  mentioned  Standard  Specifications.  A 
complete  physical  test  shall  be  made,  by  an  approved 
testing  laboratory,  of  each  size  of  bar  to  be  applied  by 
the  manufacturer  on  the  contract  from  each  ten  (10) 
ton  lot  or  less. 

These  tests  and  materials  shall  be  subject  to  the 
regulations  prescribed  in  Paragraphs  2,  4,  5a,  6d,  7,  7e, 
7f,  9 and  10  of  the  above  mentioned  specifications. 

Hot  twisted  bars  of  high  carbon  steel,  shall  be  twisted 
with  one  complete  twist  in  a length  equal  to  not  more 
than  twelve  (12)  times  the  thickness  of  the  bar. 

The  Department  of  Buildings  may  demand  the 
owner,  builder,  contractor,  sub-contractor  or  foreman 
to  make,  or  cause  to  be  made,  bending  tests  in  the 
field,  on  all  grades  of  reinforcing  steel,  when  in  their 
opinion  there  is  any  doubt  as  to  whether  the  reinforc- 
ing steel  is  up  to  the  standard  of  these  regulations. 

These  bending  tests  shall  be  those  specified  in  the, 
above  mentioned  “Standard  Specifications.” 


17 


PLACING  CONCRETE  AND  STEEL. 

Section  467,  In  filling  in  concrete  around  reinforc- 
ing steel,  the  concrete  must  be  worked  continuously 
with  suitable  tools,  as  it  is  put  in  place.  Filling  the 
columns  completely  and  puddling  afterwards  will  not 
be  permitted.  In  placing  the  concrete  the  work  shall 
be  so  laid  out  that  partially  set  concrete  will  not  be 
subjected  to  shocks  from  the  wheeling  or  handling  ma- 
terial over  it.  Concrete  placed  in  warm  weather  shall 
be  drenched  with  water  twice  daily,  Sunday  included, 
during  the  first  week  after  being  put  in  place. 

When  it  is  not  possible  to  cast  an  entire  structure 
in  one  operation,  the  work  should  be  stopped ; for  col- 
umns at  the  underside  of  girders  for  girders  at  a point 
midway  between  supports,  unless  a beam  should  occur 
at  this  point,  in  which  case  the  joint  should  be  offset 
a distance  equal  to  twice  the  width  of  the  beam;  for 
slabs  at  the  center  of  the  span. 

When  work  is  resumed  the  concrete  previously 
placed  shall  be  cleared  of  all  foreign  material,  drenched 
and  slushed  with  a mortar  composed  of  one  (1)  part 
cement  and  one  (1)  part  sand. 

Beams  and  girders  shall  not  be  constructed  over 
freshly  placed  columns  without  permitting  a period 
of  ten  (10)  hours  to  elapse  to  provide  for  settlement 
of  shrinkage  in  columns. 

Before  resuming  work  the  top  of  the  column  shall 
be  cleansed  of  foreign  matter,  and  if  the  column  has 
become  hard,  the  top  shall  be  wet  and  slushed  with 
the  cement  grout  above  specified. 

When  beams  are  designed  as  tee  beams,  the  slab 
shall  be  poured  at  the  same  time  as  the  web. 

Some  means  satisfactory  to  the  Department  of 
Buildings  shall  be  used  to  hold  the  reinforcing  steel 
in  its  proper  position  by  means  of  a spacing  and 
clamping  device. 

The  longitudinal  steel  in  beams  and  girders  shall  be 
so  disposed  that  there  shall  be  a thickness  of  concrete 
between  the  separate  pieces  of  steel  of  not  less  than 
one  and  one-half  (1J4)  times  the  maximum  sectional 
dimensions  of  the  steel. 


18 


When  steel  is  used  in  the  compressive  side  of  beams 
and  girders,  the  rods  shall  be  tied  in  accordance  with 
requirements  of  vertical  reinforced  columns,  with  stir- 
rups connecting  with  the  tension  rods  of  the  beams  or 
girders. 

FREEZING  WEATHER. 

Section  468.  When  concrete  is  placed  in  freezing 
weather,  the  materials  must  be  heated  and  such  pro- 
* visions  made  that  the  concrete  can  be  put  in  place  with- 
out freezing. 

The  use  of  frozen  lumpy  sand  or  aggregate  depend- 
ing on  hot  water  used  in  mixing  to  thaw  it  out,  will  not 
be  permitted.  All  reinforced  concrete  shall  be  kept  at 
a temperature  above  freezing  for  at  least  forty-eight 
(48)  hours  after  being  put  in  place.  All  forms  under 
concrete  placed  in  freezing  weather  shall  remain  until 
all  evidences  of  frost  are  removed  from  the  concrete 
and  the  natural  hardening  of  the  concrete  has  pro- 
ceeded to  the  point  of  safety.  All  such  work  after 
centering  is  removed  shall  be  given  the  physical  test 
prescribed  in  Section  470. 

CENTERING  AND  FORMS. 

Section  469.  All  forms  shall  be  built  in  a substantial 
manner,  plumb  and  true,  with  tight  joints,  so  that  no 
appreciable  part  of  the  concrete  mixture  can  escape, 
and  shall  be  so  supported  and  braced  that  they  will 
carry  all  the  usual  loads  which  may  come  upon  them 
without  springing  or  deflection. 

An  opening  shall  be  left  at  the  bottom  of  all  column 
forms  for  cleaning  and  adjusting  the  steel.  This 
opening  shall  not  be  closed  until  all  is  in  readiness  for 
pouring  the  columns.  The  forms  shall  be  carefully 
cleaned  just  before  concreting,  and  all  chips,  ice  and 
other  foreign  matter  removed. 

Before  removing  the  shores  under  any  beam  or 
girder  the  columns  supporting  it  shall  be  stripped,  so 
that  the  columns  may  be  examined  on  all  sides.  Pour- 
ing columns  in  chases  left  in  the  masonry  shall  not 
be  allowed. 

Provided  ample  shores  are  used  to  carry  the  full 


19 


weight  of  the  floor,  column  forms  may  be  removed 
in  not  less  than  four  (4)  days  after  pouring. 

The  time  which  shall  elapse  before  removing  the 
shores  under  beams  and  girders  varies  with  the  design 
and  condition  of  the  weather,  but  in  no  case  shall  they 
be  removed  in  less  than  three  (3)  weeks  after  pouring, 
provided  that  the  beams  and  girders  carry  their  own 
weight  only.  Where  beams  and  girders  carry  construc- 
tion loads  from  above,  sufficient  shoring  shall  be  left 
in  place  to  carry  these  loads  until  the  completion  of 
the  work. 

The  supports  under  floor  slabs  shall  not  be  removed 
in  less  than  ten  (10)  days  after  pouring,  but  this  clause 
is  not  intended  to  prevent  removing  the  joists  and  lag- 
ging in  less  time,  provided  the  slabs  are  kept  properly 
shored. 

INSPECTION  AND  TESTS. 

Section  470.  When  any  reinforced  concrete  is  used 
in  construction,  the  owner  shall  provide  for  the  in- 
spection of  cement  and  inerts,  as  required  by  the  In- 
spector of  Buildings.  Unless  otherwise  authorized  in 
writing  by  the  Inspector  of  Buildings,  the  owner  shall 
also  provide  a special  inspector  of  the  work  who  shall 
be  satisfactory  at  all  times  to  the  Inspector  of  Build- 
ings, and  who  shall  be  on  the  work  continually  during 
the  mixing  and  the  placing  of  concrete  and  steel  and  the 
removal  of  forms.  Such  special  inspector  shall  make 
daily  written  reports  to  the  Inspector  of  Buildings  on 
the  progress  of  the  work. 

Before  reinforced  concrete  work  is  started,  the 
owner  shall  name  in  writing  the  special  inspector,  and 
such  special  inspector  shall  pass  such  examination  as 
may  be  required  by  the  Inspector  of  Buildings  to  de- 
termine his  competency. 

Before  a building  containing  reinforced  concrete 
floors  is  occupied,  the  floors  shall  be  tested  by  applying 
a load  equal  to  two  and  one-half  (2*4)  times  the 
figured  live  load  to  such  parts  as  the  Inspector  of 
Buildings  or  deputies  may  select.  The  floor  shall  sus- 
tain this  load  for  at  least  twenty-four  (24)  hours, 


20 


without  cracking  or  other  evident  signs  of  failure. 

CONCRETE  BLOCK  CONSTRUCTION. 

Section  471.  (a).  Concrete  building  blocks  may  be 

used  for  building  three  (3)  stories  or  less  in  height, 
where  such  blocks  have  passed  the  test  hereinafter 
specified. 

Concrete  shall  be  composed  of  at  least  one  (1)  part 
. Portland  cement  and  not  more  than  three  (3)  parts 
w sand,  and  not  to  exceed  five  (5)  parts  crushed  rock  or 
gravel. 

The  cement,  sand  and  aggregate  shall  comply  with 
the  requirements  specified  in  Section  465  for  these  ma- 
terials. In  no  case  shall  the  walls  or  webs  of  the 
blocks  be  less  in  thickness  than  one-quarter  (%)  of 
the  height.  The  hollow  space  in  any  block  shall  not 
exceed  thirty-five  (35)  per  cent. 

(b)  The  thickness  of  walls  for  any  building  when 
concrete  blocks  are  used  shall  be  the  same  as  the  thick- 
ness of  a brick  wall,  except  where  the  allowable  crush- 
ing strength  of  such  wall  is  exceeded;  then  the  thick- 
ness must  be  increased.  An  eight  (8)  inch  block  shall 
be  considered  one  (1)  brick  thick  in  wall  measure- 
ments. 

Where  the  face  of  a building  is  of  concrete  building 
block  and  the  backing  is  of  brick  the  facing  of  con- 
crete blocks  must  be  well  bonded  to  the  brick,  with 
headers  projecting  four  (4)  inches  into  the  brick 
work,  every  fourth  course  being  a header  course.  All 
walls  where  blocks  are  used  shall  be  laid  with  Portland 
cement  mortar. 

(c)  All  concrete  blocks  before  being  used  in  con- 
struction in  buildings  shall  have  obtained  the  age  of 
at  least  four  (4)  weeks.  Such  blocks  shall  develop  a 
crushing  strength  of  fifteen  hundred  (1,500)  pounds 
per  square  inch  at  twenty-eight  (28)  days. 

Where  girders,  beams  or  joists  rest  on  the  walls 
so  that  the  end  reaction  exceeds  four  thousand  (4,000) 
* pounds  the  blocks  below  such  concentrated  loads  must 
be  made  solid  a distance  below  and  to  the  side,  as  may 
~ be  required  by  the  Department  of  Buildings. 


21 


Concrete  sills  and  lintels  spanning  over  four  (4) 
feet  six  (6)  inches  shall  be  reinforced  and  the  ends 
rest  on  solid  blocks  or  solid  walls. 

TEST  OF  CONCRETE  BLOCKS. 

Section  472.  All  concrete  materials  made  of  Port- 
land cement,  sand  and  crushed  rock  or  gravel,  or  ce- 
ment and  sand,  which  are  larger  than  the  standard  brick 
size  and  which  are  molded  and  then  set  in  place  in  the 
structure,  shall  come  under  the  provisions  as  follows : 

(a)  APPLICATION  FOR  TESTS:  Before  any 
concrete  block  is  used  in  a building  an  application  for 
its  use  and  for  a test  of  the  same  shall  be  filed  with 
the  Department  of  Buildings.  A description  of  the  ma- 
terials and  the  manufacture  of  same  shall  be  filed  with 
the  application. 

(b)  TESTS  TO  BE  MADE : The  concrete  blocks 

shall  be  subject  to  the  following  tests:  Compression, 

transverse  and  absorption. 

All  such  tests  shall  be  made  in  some  laboratory  of 
recognized  standing  under  the  supervision  of  a repre- 
sentative from  the  Department  of  Buildings.  The 
tests  shall  be  made  at  the  expense  of  the  owner. 

(c)  For  the  purpose  of  these  tests  at  least  ten  (10) 
samples  of  test  pieces  shall  be  provided.  Such  samples 
shall  be  selected  from  stock  by  a representative  from 
the  Department  of  Buildings,  or  may  be  made  in  the 
presence  of  such  representative.  The  samples  shall  be 
of  the  regular  size  as  used  in  construction,  except  that 
when  the  samples  are  too  large  to  use  in  the  ordinary 
testing  machines,  in  which  case  smaller  sized  blocks 
shall  be  made  for  testing  under  the  direction  of  a rep- 
resentative from  the  Department  of  Buildings. 

(d)  Tests  shall  be  made  in  series  of  at  least  three 
(3),  composed  of  four  (4)  samples  each.  The  trans- 
verse test  shall  be  made  on  full  size  samples.  Half  size 
samples  may  be  used  for  the  crushing  test,  and  the  re- 
maining samples  are  to  be  kept  in  reserve  in  case  ex- 
ceptionally high  values  are  shown  by  these  tests  which 
may  make  it  necessary  to  discard  certain  of  them.  All 


22 


samples  must  be  marked  for  identification  and  com- 
parison. The  weight  of  the  material  in  the  block  per 
cubic  foot  shall  be  determined. 

(e)  TRANSVERSE  TEST.  The  transverse  test 
shall  be  made  as  follows : The  samples  shall  be  placed 
flatwise  on  two  (2)  rounded  knife-edge  bearings  set 
parallel  and  seven  (7)  inches  apart.  A load  is  then  ap- 
plied on  top  of  the  test  piece  midway  between  the  sup- 
ports, and  transmitted  through  a similar  rounded  knife- 
edge  until  the  rupture  of  the  sample.-  The  modulus 
of  rupture  shall  be  determined  by  multiplying  the  total 
breaking  load  in  pounds  by  twenty-one  (21)  minus 
[three  (3)  times  the  distance  between  the  supports  in 
inches]  and  then  dividing  the  result  thus  obtained  by 
twice  the  product  of  the  width  in  inches  by  the  square 
of  the  depth  in  inches.  Allowance  shall  be  made  in 
figuring  the  modulus  of  rupture  for  the  hollow  spaces 
in  the  test  piece. 

3 WL 

Modulus  of  rupture  R = 

2 B2 

(f)  TEIE  COMPRESSION  TEST.  The  com- 
pression test  shall  be  made  as  follows : Samples  shall 

be  cut  in  blocks  in  such  a manner  as  to  contain  the 
full  web  section.  The  samples  must  be  carefully 
measured,  then  bedded  flatwise  in  plaster  of  Paris  to 
secure  uniform  bearing  in  the  testing  machine,  and 
then  crushed.  The  total  breaking  load  is  then  divided 
by  the  area  of  square  inches  in  compression.  Deduc- 
tion is  to  be  made  for  hollow  spaces. 

(g)  ABSORPTION  TEST.  The  absorption  test 

must  be  made  as  follows : The  block  is  first  to  be 

thoroughly  dried  and  weighed.  It  is  then  to  be  placed 
in  water  of  a depth  of  one-half  (^4)  inch  face  down- 
ward. After  being  in  the  water  for  thirty  (30) 
minutes,  the  block  is  again  weighed,  then  immersed  in 
water  for  four  (4)  hours  and  weighed  again.  It  is 
then  immersed  for  forty-eight  (48)  hours  and  the 
result  noted.  After  weight  is  taken  the  compressive 
strength  of  the  block  while  still  wet  is  determined  as 
provided  above. 


REQUIREMENTS  AND  CONDITION  OF  AP- 
PROVAL—REVOCAL  OF  LICENSE. 

Section  473.  (a)  The  following  requirements  must 
be  complied  with  in  order  to  secure  an  acceptance  of 
the  material : 

The  modulus  of  rupture  for  concrete  blocks  at  (28) 
twenty-eight  days  old  shall  average  one  hundred  and 
fifty  (150)  and  must  not  fall  below  one  hundred  (100) 
in  any  case. 

The  ultimate  compressive  strength  at  twenty-eight 
(28)  days  must  average  fifteen  hundred  (1500)  pounds 
per  square  inch  and  must  not  fall  below  seven  hundred 
(700)  in  any  case. 

The  percentage  of  absorption  (being  the  weight  of 
water  absorbed  divided  by  the  weight  of  the  dry 
sample)  must  not  average  higher  than  seven  (7)  per 
cent  and  must  not  exceed  ten  (10)  per  cent  in  any 
case. 

The  reduction  of  compressive  strength  must  not  be 
more  than  thirty-three  and  one-third  (33  1-3)  per  cent 
except  that  when  the  lower  figure  is  still  above  one 
thousand  (1000)  pounds  per  square  inch,  the  loss  in 
strength  may  be  neglected. 

(b)  The  approval  of  any  material  is  given  only 
under  the  following  conditions : 

A plant  for  the  production  of  the  material  must  be 
in  full  operation  when  the  official  tests  are  made. 

The  names  of  the  firms  or  corporations  and  the  re- 
sponsible officers  must  be  placed  on  file  with  the  De- 
partment of  Buildings  and  changes  in  same  promptly 
reported. 

The  Department  of  Buildings  may  require  full  tests 
to  be  repeated  on  samples  selected  from  the  open  mar- 
ket, when  in  their  opinion  there  is  any  doubt  as  to 


whether  the  product  is  up  to  the  standard  of  these 
regulations,  and  the  manufacturer  must  submit  to  the 
Department  of  Building  once  in  at  least  every  four 
months  a certificate  of  tests  showing  that  the  average 
resistance  of  three  specimens  to  cross  breaking  and 
crushing  are  not  below  the  requirements  of  these  regu- 
lations. Such  tests  must  be  made  by  some  laboratory 
of  recognized  standing,  on  samples  selected  either  by 
the  Department  of  Buildings,  or  the  laboratory  from 
materials  actually  going  into  construction,  and  not  ones 
furnished  by  the  manufacturer.  In  case  the  results 
made  under  the  preceding  divisions  show  that  the 
standard  of  these  regulations  is  not  maintained,  the 
approval  of  the  Department  of  Buildings  to  the  manu- 
facturer of  said  blocks  shall  be  at  once  suspended  and 
revoked. 

No  certificate  of  approval  shall  be  considered  in 
force  more  than  four  (4)  months,  unless  there  be  filed 
with  the  Department  of  Buildings  at  least  every  four 
(4)  months  following,  a certificate  from  some  reliable 
physical  testing  laboratory,  showing  that  the  average 
of  the  three  (3)  specimens  tested  for  compression  and 
three  (3)  specimens  tested  for  transverse  strength 
comply  with  the  requirements  of  the  Building  Depart- 
ment. 

Manufacturer  and  user  of  any  such  concrete  blocks 
as  are  mentioned  in  this  regulation,  or  either  of  them, 
shall  at  any  and  all  times,  have  made  such  test  of 
cement  used  in  making  such  blocks,  or  such  further 
tests  of  the  completed  blocks,  or  each  of  them,  at  his 
own  expense  and  under  the  supervision  of  the  De- 
partment of  Buildings  as  may  be  required. 

(c)  A license  shall  be  granted  to  those  intending 
to  manufacture  concrete  blocks,  said  license  to  be  re- 
voked for  the  following  causes : 

25 


3 0112  077859988 


Willful  violation  of  speculations,  laws  and  or] 
nances. 

Dishonest  methods. 

Use  of  improper  materials. 

Section  2.  That  Title  X,  Concrete  Constructi<j 
Sections  448,  449,  450,  451,  452,  453,  454,  455,  41 
457,  458,  459,  460,  461,  462,  463,  464,  465,  466,  4) 
468,  469,  470,  471,  472  and  473  inclusive  of  the  ij 
vised  Ordinances  of  1907,  Building  Code,  be  and  t 
same  are  hereby  repealed. 

Sec.  3.  That  this  ordinance  shall  take  effect  and ! 
in  force  from  and  after  its  passage  and  legal  public 
tion. 

Passed  Dec.  11,  1911. 


H.  F.  WALKER, 


President  of  the  Council, 
R.  Y.  McCRAY,  City  Clerk. 

Approved  by  the  Mayor,  Dec.  13,  1911. 


